Anti-inflammatory effects of Polygala tenuifolia root through inhibition of NF-κB activation in lipopolysaccharide-induced BV2 microglial cells

J Ethnopharmacol. 2011 Oct 11;137(3):1402-8. doi: 10.1016/j.jep.2011.08.008. Epub 2011 Aug 10.

Abstract

Ethnopharmacological relevance: The root of Polygala tenuifolia Willd is a well-known traditional Oriental medicine and has been prescribed for treatment of dysfunction in memorial systems and various brain inflammatory diseases. The present study was designed to validate the anti-inflammatory effects of the water extract of Polygala tenuifolia root (WEPT).

Materials and methods: The anti-inflammatory properties of WEPT were studied using lipopolysaccharide (LPS)-stimulated murine BV2 microglia model. As inflammatory parameters, the production of nitric oxide (NO), inducible NO synthase (iNOS), cyclooxygenase (COX)-2, prostaglandin E(2) (PGE(2)), tumor necrosis factor (TNF)-α, and interleukin (IL)-1β were evaluated. We also examined the extract's effect on the activity of nuclear factor-kappaB (NF-κB), and toll-like receptor 4 (TLR4) and myeloid differentiation factor 88 (Myd-88) expression.

Results: WEPT suppressed LPS-induced production of NO, PGE(2), and expression of iNOS and COX-2 in a dose-dependent manner, without causing cytotoxicity. It also significantly reduced generation of proinflammatory cytokines, including IL-1β and TNF-α. In addition, WEPT suppressed NF-κB translocation by blockade of IkappaB-α (IκB-α) degradation and inhibited TLR4 and Myd-88 expression in LPS-stimulated BV2 cells.

Conclusions: These results indicate that the inhibitory effects of WEPT on LPS-stimulated inflammatory mediator production in BV2 microglia are associated with suppression of the NF-κB and toll-like receptor signaling pathways. Therefore, Polygala tenuifolia extracts may be useful in treatment of neurodegenerative diseases by inhibition of inflammatory mediator production in activated microglia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Inflammatory Agents / isolation & purification
  • Anti-Inflammatory Agents / pharmacology*
  • Cell Line
  • Cyclooxygenase 2 / metabolism
  • Dinoprostone / metabolism
  • Dose-Response Relationship, Drug
  • I-kappa B Proteins / metabolism
  • Inflammation Mediators / metabolism
  • Interleukin-1beta / genetics
  • Interleukin-1beta / metabolism
  • Lipopolysaccharides / pharmacology*
  • Mice
  • Microglia / drug effects*
  • Microglia / immunology
  • Microglia / metabolism
  • Myeloid Differentiation Factor 88 / metabolism
  • NF-KappaB Inhibitor alpha
  • NF-kappa B / metabolism*
  • Nitric Oxide / metabolism
  • Nitric Oxide Synthase Type II / metabolism
  • Plant Extracts / isolation & purification
  • Plant Extracts / pharmacology*
  • Plant Roots
  • Plants, Medicinal
  • Polygala* / chemistry
  • RNA, Messenger / metabolism
  • Solvents / chemistry
  • Toll-Like Receptor 4 / drug effects
  • Toll-Like Receptor 4 / metabolism
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / metabolism
  • Water / chemistry

Substances

  • Anti-Inflammatory Agents
  • I-kappa B Proteins
  • Inflammation Mediators
  • Interleukin-1beta
  • Lipopolysaccharides
  • Myd88 protein, mouse
  • Myeloid Differentiation Factor 88
  • NF-kappa B
  • Nfkbia protein, mouse
  • Plant Extracts
  • RNA, Messenger
  • Solvents
  • Tlr4 protein, mouse
  • Toll-Like Receptor 4
  • Tumor Necrosis Factor-alpha
  • lipopolysaccharide, E. coli O26-B6
  • Water
  • NF-KappaB Inhibitor alpha
  • Nitric Oxide
  • Nitric Oxide Synthase Type II
  • Nos2 protein, mouse
  • Ptgs2 protein, mouse
  • Cyclooxygenase 2
  • Dinoprostone